President Obama participates in the wreath-laying ceremony at the Tomb of the Unknowns at Arlington National Cemetery on Memorial Day, May 27 in Arlington, Va. (Pablo Martinez Monsivais/AP)

ARLINGTON, VA. — President Obama said Monday that Americans must honor the sacrifices of their fighting men and women, particularly at a time when the U.S. combat role in Iraq has ended and the country’s involvement in Afghanistan is winding down.

Speaking at Memorial Day ceremonies at Arlington National Cemetery, Obama said he worries that the country’s servicemen and women aren’t being fully appreciated in an era in which “most Americans are not directly touched by war.” He said he couldn’t explain that phenomenon but said it might have something to do with the all-volunteer military force and advanced technology that now permits the United States to accomplish some military missions with far fewer personnel.

But Obama did say that even as “we turn a page” away from Iraq, and Afghanistan by the end of 2014, “let us never forget that the nation is still at war.”

He said that some troops and military families “mention to me their concern about whether the country fully appreciates” them.

Obama’s Memorial Day appearance at the venerable Arlington burial grounds came four days after he declared in a major national security address that the U.S. has taken down the al-Qaida terrorist organization, particularly in the aftermath of the killing of leader Osama bin Laden, although terrorist threats remain and the country cannot afford to let its vigilance slide.

Obama spoke on a sun-splashed morning at the amphitheater of Arlington National Cemetery after he placed a wreath at the Tomb of the Unknowns. That was preceded by a playingof the National Anthem and followed by the placing of “Taps.”

In his speech, he said that Arlington “has always been home to men and women who are willing to give their all ... to preserve and protect the land that we love.”

He praised the selflessness that “beats in the hearts” of America’s uniformed military troops.

Keeping with a tradition he established earlier in his presidency, Obama stopped at Section 60 before departing and walked among the graves of the war dead from Iraq and Afghanistan.